Chris Kirchner previously attempted to buy Preston North End
Derby County's administrators have exchanged contracts for the sale of the club with Chris Kirchner.
American businessman Kirchner will fund the club from next week, and says he doesn't "anticipate any issues" completing the process of the sale.
In a statement, Quantuma said the exchange was "conditional on the sale of the stadium, EFL approval and receiving secured creditor consent".
Completion of the sale is targeted for on or before 31 May.
Preferred bidder Kirchner said on Twitter:external-link "Today is a day I'll never forget. I'm humbled and excited to share that we've exchanged contracts with Quantuma and I will be the next owner of Derby County Football Club."
He added: "My team is now moving forward on the process to rebuild this iconic club. This has been a traumatic period for everyone and I can say that I hope this is the most difficult transaction I have to complete for a very long time."
Quantuma said: "The period of time between exchange and completion will allow the joint administrators and all relevant stakeholders the time required to work together to meet the conditions required to complete this very complex transaction."
Derby were placed in administration in September and docked 21 points over the course of the season because of that and breaches of EFL financial rules. The penalties contributed to the Rams being relegated from the Championship and into the third tier for the first time since 1986.